Linux: validate RTM_NEWADDR/RTM_DELADDR for AF_INET as well.

diff --git a/src/if-linux.c b/src/if-linux.c
index 4fd5d265a68ab19a423fcfc707b09028f1955583..a2f590bf29d2b3704c5852f3a324397f6dc1a6c5 100644 (file)
--- a/src/if-linux.c
+++ b/src/if-linux.c
@@ -125,6 +125,8 @@ static const uint8_t ipv4_bcast_addr[] = {
 };
 #endif
 
+static int if_addressexists(struct interface *, struct in_addr *);
+
 #define PROC_INET6     "/proc/net/if_inet6"
 #define PROC_PROMOTE   "/proc/sys/net/ipv4/conf/%s/promote_secondaries"
 #define SYS_BRIDGE     "/sys/class/net/%s/bridge"
@@ -445,7 +447,7 @@ recv_again:
                return 0;
 
        r = 0;
-       again = 0;      /* Appease static analysis */
+       again = 0;
        for (nlm = iov->iov_base;
             nlm && NLMSG_OK(nlm, (size_t)len);
             nlm = NLMSG_NEXT(nlm, len))
@@ -684,7 +686,16 @@ link_addr(struct dhcpcd_ctx *ctx, struct interface *ifp, struct nlmsghdr *nlm)
                        rta = RTA_NEXT(rta, len);
                }
 
-               /* XXX how to validate command for address? */
+               /* Validate RTM_DELADDR really means address deleted
+                * and anything else really means address exists. */
+               if (if_addressexists(ifp, &addr) == 1) {
+                       if (nlm->nlmsg_type == RTM_DELADDR)
+                               break;
+               } else {
+                       if (nlm->nlmsg_type != RTM_DELADDR)
+                               break;
+               }
+
                ipv4_handleifa(ctx, nlm->nlmsg_type, NULL, ifp->name,
                    &addr, &net, &brd, ifa->ifa_flags, (pid_t)nlm->nlmsg_pid);
                break;
@@ -906,6 +917,7 @@ send_netlink(struct dhcpcd_ctx *ctx, void *arg,
     int (*callback)(struct dhcpcd_ctx *, void *, struct nlmsghdr *))
 {
        int s, r;
+       bool privsock;
        struct sockaddr_nl snl = { .nl_family = AF_NETLINK };
        struct iovec iov = { .iov_base = hdr, .iov_len = hdr->nlmsg_len };
        struct msghdr msg = {
@@ -913,7 +925,8 @@ send_netlink(struct dhcpcd_ctx *ctx, void *arg,
            .msg_iov = &iov, .msg_iovlen = 1
        };
 
-       if (protocol == NETLINK_ROUTE) {
+       privsock = (protocol == NETLINK_ROUTE && hdr->nlmsg_type != RTM_GETADDR);
+       if (privsock) {
                struct priv *priv;
 
                priv = (struct priv *)ctx->priv;
@@ -921,6 +934,16 @@ send_netlink(struct dhcpcd_ctx *ctx, void *arg,
        } else {
                if ((s = _open_link_socket(&snl, protocol)) == -1)
                        return -1;
+
+#ifdef NETLINK_GET_STRICT_CHK
+               if (hdr->nlmsg_type == RTM_GETADDR) {
+                       int on = 1;
+
+                       if (setsockopt(s, SOL_NETLINK, NETLINK_GET_STRICT_CHK,
+                           &on, sizeof(on)) == -1)
+                               logerr("%s: NETLINK_GET_STRICT_CHK", __func__);
+               }
+#endif
        }
 
        /* Request a reply */
@@ -936,7 +959,7 @@ send_netlink(struct dhcpcd_ctx *ctx, void *arg,
                r = get_netlink(ctx, &riov, arg, s, 0, callback);
        } else
                r = -1;
-       if (protocol != NETLINK_ROUTE)
+       if (!privsock)
                close(s);
        return r;
 }
@@ -1259,6 +1282,60 @@ struct nlma
        char buffer[64];
 };
 
+#ifdef INET
+struct ifiaddr
+{
+       unsigned int ifa_ifindex;
+       struct in_addr ifa_addr;
+};
+
+static int
+_if_addressexists(__unused struct dhcpcd_ctx *ctx,
+    void *arg, struct nlmsghdr *nlm)
+{
+       struct ifiaddr *ia = arg;
+       in_addr_t this_addr;
+       size_t len;
+       struct rtattr *rta;
+       struct ifaddrmsg *ifa;
+
+       ifa = NLMSG_DATA(nlm);
+       if (ifa->ifa_index != ia->ifa_ifindex || ifa->ifa_family != AF_INET)
+               return 0;
+       rta = (struct rtattr *)IFA_RTA(ifa);
+       len = NLMSG_PAYLOAD(nlm, sizeof(*ifa));
+       while (RTA_OK(rta, len)) {
+               switch (rta->rta_type) {
+               case IFA_LOCAL:
+                       memcpy(&this_addr, RTA_DATA(rta), sizeof(this_addr));
+                       return this_addr == ia->ifa_addr.s_addr ? 1 : 0;
+               }
+               rta = RTA_NEXT(rta, len);
+       }
+       return 0;
+}
+
+static int
+if_addressexists(struct interface *ifp, struct in_addr *addr)
+{
+       struct ifiaddr ia = {
+               .ifa_ifindex = ifp->index,
+               .ifa_addr = *addr,
+       };
+       struct nlma nlm = {
+           .hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
+           .hdr.nlmsg_type = RTM_GETADDR,
+           .hdr.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+           .ifa.ifa_family = AF_INET,
+           .ifa.ifa_index = ifp->index,
+       };
+
+       return send_netlink(ifp->ctx, &ia, NETLINK_ROUTE, &nlm.hdr,
+           &_if_addressexists);
+}
+#endif
+
+
 struct nlmr
 {
        struct nlmsghdr hdr;